The setup process works differently depending on your phone model and Android version. Google Pixel phones have it mapped to the power options(most do or can be enabled). Example Samsung phones must activate the feature in the Settings menu before it appears among power options. Some Android devices don't support it.
but as always there is an app for that(one that have used on devices without lockdown mode built-in)
All lockdown mode does is stop your device from being unlocked with biometrics it doesn't change your actual biometrics set up either
Once you long press power button then enable lockdown mode your device won't be able to unlock without password or pin or pattern - once its unlocked the biometrics works as normal - you have to enable lockdown mode again when turning screen off or your biometrics will be able to unlock - keep in mind >> long press power hit lockdown when out & about
This app once installed will add shortcuts to your notifications quick settings tiles for enabling lockdown mode - using lockdown mode becomes part of your routine after a while you'll find yourself using it while out and about then while at home you'll be back to biometrics for unlocking device - like most things it becomes second nature you do it without thinking
/nosanitize
https://play.google.com/store/apps/details?id=com.radefffactory.lockdown